The present invention relates to a method for displaying acquired data from a system under test and more specifically to a method for symbolically displaying acquired time domain reflectometry data.
With the increased capabilities of modern test equipment to acquire and display data, it becomes much more difficult for a user to assimilate and interpret the information being presented on a display screen. Such products as oscilloscopes, spectrum analyzers, logic analyzers, and time domain reflectometers provide the user with multiple readouts, cursors, and displays which, in many cases, must be interpreted by the user. This requires the operator to have a high level of training and experience with the test equipment and in the technical area in which the operator works.
In testing fiber optic cables, an operator uses an optical time domain reflectometer, OTDR, to locate reflections and faults in the fiber optic cable. The OTDR display generally consists of an amplitude versus time plot on a cathode ray tube showing a generally decreasing amplitude of a return signal representing the backscatter from the fiber optic cable. Reflections from splices and the like appear as pulses on the backscatter ramp and generally result in some loss. Also losses may be encountered in the optical cable in the absence of reflections.
In performing tests on fiber optic cables, an operator must have some knowledge of the length of the cable, cable splice locations, and the losses associated with these splices. The operator then manually sets-up the OTDR using front panel controls by selecting the vertical and horizontal scale, the pulse length of the transmitted signal, and the like. After the data is acquired and displayed, the operator manually manipulates the front panel controls to determine parameters, such as cable length, distance to an event, e.g. reflection or loss, and the average loss of the cable. It is possible in such tests that significant events could be overlooked if the OTDR was not set-up properly or the operator misinterpreted the display.
What is needed is test equipment that requires substantially less training and experience for an operator. The test equipment should have the capability to be easily set-up and provide a display that presents the data in a form that does not require interpretation by the operator.